Having always dreamed of being a young dad, O-Town hunk Jacob Underwood was on the verge of giving up his hopes of fatherhood, but has now proudly welcomed his first child, a baby girl named Everest Bay Underwood!

“I always thought I’d be a young dad, which is funny because I’m not,” Jacob tells ET. “I’m 38, so not too far gone, but I almost started going, ‘Man, maybe it’s just not going to happen because I haven’t found the right person.’ But you never know what God has in store for you. Finding out we were pregnant was a shocker!”

Jacob's patience to become a father was further tested through a long labor, which saw Chandler rushed into inducement due to a mild case of cholestasis, which can endanger a baby's health. Three days of failed induction attempts followed before her water was broken. Another 24 hours later, doctors found Everest's umbilical cord was wrapped around her neck and shoulder, meaning she was immediately put on life support for several moments after her birth.

"It felt like a lifetime of waiting before hearing that beautiful cry and knowing she was going to be okay," Chandler says. "It was every emotion wrapped into one as we got to hold her and cry together at the miracle we just witnessed. Thankfully, she's completely healthy and as beautiful as we could have ever imagined."

"I think we both have a new found love and respect for each other after having gone through such an exhausting and emotional few days," Jacob adds. "We’ve had a hard time putting her down and spend most of the day just watching her. We find her the most entertaining and beautiful thing in the world and we're honored to be her parents."

Jacob Underwood

Jacob Underwood

Jacob Underwood

With his fatherhood fantasies finally coming to fruition, the musician’s now relishing family life with his baby girl, who was named after Mount Everest, in honor of Chandler’s late mom. While Jacob initially had doubts, the unique name has since grown on him.

“My mom was an amazing, adventurous, crazy woman and her big dream was to hike Mount Everest, but that never happened before she passed away eight years ago,” Chandler, a 28-year-old singer-songwriter explains. “I kept thinking it could be very symbolic of the relationship I had with my mom. This is like my Everest that I’m now climbing with my daughter.”

The couple, who met in 2016 after Jacob was wowed watching Chandler perform at a Nashville karaoke bar and signed on to become her manager, found out they were pregnant in February. Just two weeks earlier, they had discussed the possibility of putting music aside to start a family in another couple of years, but Jacob says, “God laughed at our plan.” As well as being a joyful surprise, the pregnancy also sparked a huge sigh of relief for the pair, who finally had an explanation for the “hormonal rollercoaster” that Chandler had been riding.

“I had been losing my mind and so tired,” recalls Chandler, who eventually decided to take a pregnancy test. “I was sleeping 15 hours a day and thought I was really depressed. I told him, ‘I’m going through something right now and I don’t know what it is, but just bear with me.’ We were in the middle of talking about what was going on with me when I went to the bathroom and saw the results, then I was like, ‘Just so you know, it’s positive.’ He was like, ‘Wait. What? What’s positive?’ and I said, ‘I just took a pregnancy test!’ That’s when all the confusion of what was going on with me made sense. He was like, ‘My girlfriend’s not crazy!’”

“I thought she’d lost her mind!” Jacob laughs. “I felt so much more peace after that.”

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The news was a surprise for Chandler, who grew up in Massachusetts, the second youngest of eight siblings, and was admittingly more accustomed to “being the kid” than having one. Unsure if she would ever become a mom, and thinking she would have two sons if she did, her doubts were quelled when she saw the look on Jacob’s face after he heard he was going to be a dad. “The smile on his face just lit up my world and made it all feel like a fairytale,” she gushes.

However, another shock was in store as Chandler and Jacob -- who also envisioned having sons -- discovered they were having a girl.

“I was like, ‘Oh s**t, my world just changed. In all the best ways, but it’s so different,’” shares Jacob, who proposed to Chandler at the Eiffel Tower in Paris, France, in May. “I have three buddies all having girls right now and everybody’s saying how it’s such a different feeling knowing you’re going to be responsible for a little girl instead of a little boy.”

Of course, being a girl means Jacob, O-Town and their fellow boy bands have one more fangirl in their armies, with the couple revealing that Everest developed her great musical taste early on. While Jacob played Michael Jackson every night to her belly, it was a rival boy bander who really got little Everest busting a move in the womb!

“Ironically, she reacted the most to Justin Timberlake’s song, ‘Say Something,’” Chandler says. “We were blasting that song and it was the first time I felt her come right to the surface kicking. She already knew she was a from a boy bander! She was the same when I went to see Jacob’s shows with O-Town. She’d really react to live music, which is the coolest feeling ever as a mom.”

“She’s already a Justin fan!” Jacob adds.

Now, as Jacob, who has a business degree and manages O-Town, prepares to go back on the road with the “All Or Nothing” singers in November, then release the group’s Kickstarter campaign-funded EP in 2019, the couple are also busy working on Chandler’s upcoming EP, with Jacob still managing and producing her music. The pair, who previously released a cover of Gnash’s “I Hate You, I Love You,” may also duet again together in the future.

“The music we’ve been working on really grew, evolved and became so meaningful,” she says. “Once I got pregnant, all these songs that I didn’t know what to do with before started making sense -- as if they had been waiting for her to come. So, the songs are really geared around my love for Jacob and now our baby girl.”

Jacob Underwood

Jacob Underwood

Jacob Underwood

Then, of course, there’s a wedding to plan!

The two got engaged in May, with Jacob having planned the proposal with his bandmates for months, then deciding he'd better “get my nerves together and just do it,” after learning about the pregnancy. He then nervously made it through multiple metal detectors at the Eiffel Tower with the ring before getting down on one knee. With music and Everest now keeping them busy, the pair are yet to set a date for the nuptials.

“We talked about having Everest be in the wedding,” says the Dead 7 star. “With so much life happening and so much stuff planned right now, we don’t want to do a shotgun wedding. We want it to be everything we hoped it would be and to have our daughter be a part of it will be that much more special.”

In the meantime, Jacob’s simply pinching himself to be living the life he always hoped for.

“Neither of us were expecting this when we met, but you just can’t plan for these things,” he reflects. “It’s like as soon as I told my friends, ‘I am done with dating, the girl I want is not out there,’ two months later she popped into my life.”